title: Morphological plasticity of Streptococcus oralis isolates for biofilm production, invasiveness, and architectural patterns.
abstract: OBJECTIVE
  Streptococcus oralis is an early coloniser of the oral cavity that contributes to dental plaque formation. Many different genotypes can coexist in the same individual and cause opportunistic infections such as bacterial endocarditis. However, little is known about virulence factors involved in those processes. The aim was to analyze the evolving growth of S. oralis colony/biofilm to find out potentially pathogenic features.
  
  
  METHODS
  Thirty-three S. oralis isolates were analyzed for: (1) biofilm production, by spectrophotometric microtiter plate assay; (2) colonial internal architecture, by histological methods and light and electron microscopy; (3) agar invasion, by a new colony-biofilm assay.
  
  
  RESULTS
  S. oralis colonies showed two different growth patterns: (1) fast growth rate without invasion or minimally invasive; (2) slow growth rate, but high invasion ability. 12.1% of strains were biofilm non-producers and 24.2% not invasive, compared to 51.5% biofilm high-producers and 39.4% very invasive. Both phenotypic characteristics tended to be mutually exclusive. However, a limited number of strains (15%) co-expressed these features at the highest level.
  
  
  CONCLUSIONS
  Morphological plasticity of S. oralis highlighted in this study may have important ecological and clinical implications. Coexistence of strains with different growth patterns could produce a synergic effect in the formation and development of subgingival dental plaque. Moreover, invasiveness might regulate dissemination and colonisation mechanisms. Simultaneous co-expression of high-invasive and high-biofilm phenotypes gives a fitness advantage during colonisation and may confer higher pathogenic potential.
authors.affiliation: Department of Pathology, Carlos III Hospital, Madrid, Spain.
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Corcuera
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Gómez-Lus
authors.forename: Fernando
authors.initials: F
authors.lastname: Gómez-Aguado
authors.forename: Juan Ramón
authors.initials: JR
authors.lastname: Maestre
authors.forename: María del Carmen
authors.initials: Mdel C
authors.lastname: Ramos
authors.forename: María José
authors.initials: MJ
authors.lastname: Alonso
authors.forename: José
authors.initials: J
authors.lastname: Prieto
mesh_terms: D001431:Bacteriological Techniques; D018441:Biofilms / Q000254:growth & development*; D003773:Dental Plaque / Q000382:microbiology*; D006801:Humans; D009055:Mouth / Q000382:microbiology*; D013053:Spectrophotometry; D019533:Streptococcus oralis / Q000166:cytology / Q000254:growth & development* / Q000472:pathogenicity; D037521:Virulence Factors
chemical_list: D037521:Virulence Factors
keywords: Biofilm; Colonial architecture; Invasiveness; Streptococcus oralis